The phospholipidomic signatures of human blood microparticles, platelets and platelet-derived microparticles: A comparative HILIC-ESI-MS investigation

The phospholipidomic signatures of human blood microparticles and platelets, evaluated by hydrophilic interaction liquid chromatography coupled to electrospray ionization - mass spectrometry, were compared. The phospholipidome of platelet-derived microparticles, obtained by platelets stimulation with a mixture of Ca(II), thrombin and collagen, was also considered for the comparison. Platelets, blood microparticles and platelet-derived microparticles displayed qualitatively similar phospholipidomes, all based on eight major phospholipid classes, namely: phosphatidylcholines, diacyl- and plasme(a)nyl-phosphatidylethanolamines, phosphatidylserines, phosphatidylinositols, sphingomyelins and lyso forms of phosphatidylcholines and phosphatidylethanolamines. However, while the phospholipidomes of platelets and platelet-derived microparticles were found to be generally similar also from a quantitative point of view, a higher relative incidence of species bearing polyunsaturated side chains, especially in phospholipid classes sharing the choline head (i.e. phosphatidylcholines and lyso-phosphatidylcholines), was observed in the case of blood microparticles. As a further peculiar feature, never reported before, the relative abundance of lyso-phosphatidylcholines among the eight identified phospholipid classes was found to be significantly higher in the lipid extracts of blood microparticles.